Steve M
Enthusiast
I don't think that's too much to ask.
Gen V dyno - New Vid
- Thread starter ACRucrazy
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I don't think that's too much to ask.
mnc2886
Enthusiast
Keep in mind that when the car was first put on a dyno by Edmunds Ralph himself said it should be 580.
I meant overrated in terms of HP. I know how great the car is, its a VIPER!
Third gear is usually 1:1 if no changes were made to the vehicle, and that's the gear used in a dyno test. If your car comes stock with 3.07 and you change to 3.55 or 4.10 gears then 3rd gear would no longer be 1:1 and you'd see higher dyno numbers, which would have to be compensated for to get accurate HP/TQ figures.
Overrated in terms of HP and Torque ratings? The dyno would have had to have been off by more than 20% for that to be a valid claim. The Gen 4 was a Honda S2000 with a V10 and weak sales proved it...I wouldn't go so far as to call it a legend so much as an exercise in what the Viper is not.
Dyno pulls are done in 4th gear. If the gearing is shortened, as in numerically increased, going from 3.07 to 3.55 then measured power decreases. Calling a gen3,4 an S2000 is like calling a ZR1 a TR6 with a V8. By legend I think he means subjectively due to be the 'ring King, holding several spots in fastest lap records at numerous tracks, etc. Kinda just like the S2000. That's a whole lotta wrong in that post. Oh this gen5 forum is a weird place.
Steve M
Enthusiast
Well, if a Gen IV is an S2000 with a V-10, then a Gen V is an S2000 with a V-10 and a nice interior. You are right...there's definitely a different vibe in here, and that doesn't appear to be a good thing.
Steve M
Enthusiast
Here...read this article:
http://www.hotrod.com/techfaq/hrdp_0405_chassis_dyno_guide/viewall.html
4th gear is 1:1...it stays 1:1 regardless of rear axle ratio. That's why the rear axle ratio is a variable input for any dyno...if you told the dyno it was a 3.07 and you really had 3.55s back there, the dyno would read a higher number due to the torque multiplication advantage of the 3.55s. If you give it the correct input, it will divide the rear axle ratio out to get back to 1:1 (all power going through the mainshaft of the transmission).
What Tony brings up is accurate for an inertial dyno (e.g. DynoJet)...a car originally dyno'd with a 3.07 rear end and then run again with the only change being 3.55s will show a lower output due to inertial losses. The dyno computer is told how to account for the change in gear ratios, but an inertial dyno only cares how fast you accelerated the drums. I've seen enough dyno results from cars with only gear swaps to know that this occurs pretty regularly and is repeatable. Put 3.07s in a Gen V, and you'd see those dyno numbers creep up probably around 10 or so HP at the wheels. Of course, it'd be a **** on the street with a retardedly tall first gear, but that's beside the point.
ViperGeorge
Enthusiast
Why is this true? I would think that the amount of horsepower to turn the driveline would be a constant based on the design of the driveline. In other words why would two cars with the same driveline (say a Gen 3 and a Gen 4) require different amounts of absolute HP to turn the driveline? If a 500HP gen 3 lost 75HP to the driveline wouldn't a Gen 4 with the same driveline also lose 75HP to the driveline? In this example the Gen 3 would put 425 to the wheels and the Gen 4 would put 525 to the wheels.
Makara
Viper Owner
It doesn't really work that way. First off, fourth gear is a 1:1 ratio. That means the input shaft and the output shaft are spinning at the same rate. This yields the least amount of parasitic loss. The final drive has nothing to do with the 1:1 figure. This is how much the driveshaft spins in relation to the wheels. The further you get from a 1:1 ratio, the more gears are spinning to increase or (far more likely in automotive applications) decrease the rate of wheel rotation, the more power is lost to heat. This is why the 3.07 will be slightly more efficient in power delivery than the 3.55. I don't believe that the difference is huge, but there should be a slight difference.
Makara
Viper Owner
Why is this true? I would think that the amount of horsepower to turn the driveline would be a constant based on the design of the driveline. In other words why would two cars with the same driveline (say a Gen 3 and a Gen 4) require different amounts of absolute HP to turn the driveline? If a 500HP gen 3 lost 75HP to the driveline wouldn't a Gen 4 with the same driveline also lose 75HP to the driveline? In this example the Gen 3 would put 425 to the wheels and the Gen 4 would put 525 to the wheels.
More power means a higher rate and/or more torque. In either case, more friction is encountered as gears are either spinning quicker or have more force being applied to them. Either scenario creates more heat.
Hold out your left arm and slowly rub back and forth without much pressure with your right hand. Not too much heat, is it? Now rub back and forth as quick as you can. Feel the heat build up? Now apply more pressure down. More heat? Getting tired? This is kinematic energy being transferred into heat. Heat doesn't spin wheels.
The cars that I have had dyno tuned were done on 3rd gear of a 6-speed trans, although you're stating it as if it is the same for all cars it's not. You get the best results by pulling in the gear that gives you the closest 1:1 ratio, which can vary based on the gearing of the transmission and final drive, and is typically but not always 3rd gear on a 5-speed trans and 4th gear on a 6-speed.
The gears are physically larger as the number increases, and it takes more revs to turn the taller gears than it does the shorter gears. Due to the way a dynojet works, this creates the "illusion" of lower power, which is more of a limitation of the method of measuring torque on a dyno.
BTW power is not measured; torque is measured while power is calculated, since we're nit-picking here.
You can post great lap times in a shifter cart - that doesn't make shifter carts legendary. The Gen 4 has its niche following, but the vast majority of people probably will write it off as a fast S2000. Sorry man, that's what you get when you design purely for function to the exclusion of aesthetics. The Gen 5 got it right 100% across the board.
Nothing I said was wrong although you probably disagree...
Not sure you're going to find many people backing your claim on that one.
The Gen 4 LOOKS LIKE an S2000 plain and simple. It does not look like a Viper, it is not distinctive and it strayed far off course trying to make the Viper something it is not. All it has is performance, which isn't enough to be worthy of the Viper nameplate on its own...the Gen 5 improved upon the Gen 4s performance and gave the car its soul back. The Gen 5 is instantly recognizable as a Viper. The only vibe I'm getting is insecure gen 4 owners...no need for that. Just trade it in and get yourself a gen 5.
Half false. The gearing of the transmission determines whether 3rd or 4th gear are the closest or equal to 1:1. True that the axle ratio does not affect the ratio.
This is why taller gears post lower dyno numbers but it also serves as a reminder that dyno numbers are not "set in stone" and should only be used for comparative tuning, to see if changes you make to the engine result in higher or lower numbers after getting a baseline reading. In other words, no need to complain about the Gen 5 dyno numbers being "too low" or "not impressive" as some others have stated, because the numbers you get on the dyno are quite fuzzy. The best numbers to go by are averages or median lap times, ETs, trap speeds etc.
It could be on certain transmissions but it is not always. Like I said before, it depends on the gearing of the transmission and it is usually 3rd or 4th gear, however that doesn't mean that it is a true 1:1 ratio. Sometimes you just have to settle for getting it as close as possible.
The taller gears post lower numbers on the dyno due to the way the dyno works. The dyno drum measures the time it takes a car to spin the drum up to a preset RPM. Taller gears require more revs to spin the wheels, and therefore the drum, so the engine has to spend more time overcoming its own inertia as well as that of the driveline.
The HP/TQ loss at the wheels isn't really about heat so much as it is the power required to accelerate the mass of the driveline components. Power (in physics) is "work" done over time, and since engines produce torque, and the amount of torque required to turn the drivetrain of a car does not increase as the power of the engine increases.
If you took a car that was rated at 600 ft-lbs @ crank stock, with 510 ft-lbs @ wheels (15% driveline loss), you can infer that it takes 90 ft-lbs of torque just to turn the drivetrain before the car would accelerate.
Let's say you slapped on a turbo to this engine and gained 300 ft-lbs at the crank, but did nothing to the rest of the car. The torque required to turn the drivetrain will not magically increase - it is still 90 ft-lbs. So now you have an engine with 900 ft-lbs @ the crank - what you should expect to at the wheels? The answer is 810 ft-lbs, which is only a 10% driveline loss.
The basic point is that as engine power increases you should see a decrease in the percentage of HP/TQ lost to the drivetrain. The common internet theory of the driveline loss being a fixed percentage regardless of power is incorrect. You'd actually want to calculate your driveline loss while the car is stock, then after doing any work to improve the power of the engine you would go by the static ft-lb value you got initially.
ViperGeorge
Enthusiast
Thanks PeerBlock. Exactly what I was saying.
You were saying the Gen IV are going to be written off by the vast majority of people as a fast S2000?
You made 1 post prior in this thread and you seem to be the one who thinks 1:1 in the Viper is 3rd gear.. No one else.
We are all on the same page here. We are talking about the Vipers. We are not talking about your previous cars or 5 speeds.
Oh, but I was talking about my other cars and cars in general as they pertain to dyno results, with the point being that the figures presented in this video are not indicative of the Gen 5 having optimistic power ratings. Whether or not you dyno the viper in 3rd or 4th gear is irrelevant - whatever gear puts you as close to 1:1 as possible is where you should be and if that's 4th gear on the viper, great...on a lot of the other cars I've owned it was 3rd gear. Why get sidetracked with this minutia? You're not mad about the gen 4 being a fast S2000 thing, are you?
That's great. And known. But we are talking about the Viper.
Not at all. My fast S2000 is like a circus on wheels. It seems to get all kinds of attention every time the garage door opens. I don't get it.
The discussion is black and white, it is not about what is close to 1:1. There is always a gear that is exactly 1:1, Again, it is, black and white, in a T56 or 6060 fourth gear is 1:1. Everyone dyno's those cars in 4th gear. As was stated before, the input and output shafts are at the same rpm. In addition, as was stated previously, the parasitic losses are greater in a 3:55 versus a 3:07, however, the difference is almost inconsequential.
bushido
Viper Owner
That's great. And known. But we are talking about the Viper.
Not at all. My fast S2000 is like a circus on wheels. It seems to get all kinds of attention every time the garage door opens. I don't get it.
Yup the Gen 4 ACR Viper is the meanest looking viper period. If I park my ACR next to a Gen V . It would make the Gen V disappear.
That's great. And known. But we are talking about the Viper.
Not at all. My fast S2000 is like a circus on wheels. It seems to get all kinds of attention every time the garage door opens. I don't get it.
No, we're talking about dyno numbers and how they pertain to the viper, as well as other vehicles...but feel free to try to keep telling everyone what they are talking about since you know better.
Just watch it when your S2000 hits VTEC because it gets a bit squirrely with all those powers its producing.
Not all transmissions have a 1:1 exact match gear. Not sure how to state that any more plainly. You could say that "many" transmissions have a 1:1 gear, but you are wrong to say that all do. The hang up on gear ratio is ignoring the point of the post - that dyno numbers are not a very good way to compare vehicle performance among various generations of a particular car or cars in general.
Yup the Gen 4 ACR Viper is the meanest looking viper period. If I park my ACR next to a Gen V . It would make the Gen V disappear.
Yeah, it is pretty mean for a honda.
Only if those $14,000 paint jobs weren't holding the Gen V's back, then the VTEC could really put down some powers.
Makara
Viper Owner
We are talking about vipers and 4th gear is 1:1
But the higher rate at a reduced torque should equal it's self out when calculated into power unless less power is actually being delivered.
Umm, no, it's about heat. Remember conservation of energy? That energy lost between the engine and the wheels goes somewhere, and that is mostly heat. Energy doesn't just disappear, it is transferred to another type of energy.
Actually, you can't infer that at all. Tricky of you to put in a torque value rather than power, but either way, the parasitic loss of a transmission is not the same at full power as it is at low power. The greater the power, the greater the loss. Drive your car lazily and see how hot the transmission tunnel gets. Now drive the crap out of it at the race track and see how hot it gets. Where is that heat coming from? Transference of energy, from kinetic to thermal. Conservation of energy...
You are dead right, it doesn't magically increase, it increases because of physics which it turns out isn't magic at all. Let's say that engine is outputting the same power with the turbo as it did without under the current load, the parasitic loss would be the same as before it had the turbo on it. Once the load is increased and power output rises, the losses will be greater, mostly due to heat.
You started off correct. It isn't a fixed percent of power loss. There is a certain amount of power required to turn a transmission and beyond that, a portion of the power produced will be lost, but a fixed percentage seems to be a rather decent guideline to work off of. You don't want to calculate your stock driveline loss and assume that at all loads and all power outputs it will be the same because that is quite inaccurate. If a viper engine required 100 hp just to spin it's transmission at any speed, our engines would be working a heck of a lot harder when pulling into a parking spot.
Makara
Viper Owner
The zero loss transmission is only available with the perpetual motion engine. The technology has been around for years but the oil companies don't want you to know about them
Nine Ball
Enthusiast
I'll take the lower dyno number and 3.55 gears. The car accelerates quicker with the revised gear ratio, despite what dynojet numbers say. It gets into the racing powerband much quicker than the Gen 4.
Tony
Tony
ViperGeorge
Enthusiast
No. Go back and read my posts in this thread. I was saying that it should take the absolute same amount of horsepower (or torque if you prefer) to turn the drive train in two cars with the same driveline design. It should not (and I believe it does not) depend on the amount of power the engine is able to create. Given I actually do have a degree in physics I would love for someone to show me the "physics" behind this number increasing just because the power of the engine increases.
Nine Ball
Enthusiast
There is a 1:1 (technically 1.00) gear ratio in just about every transmission ever built. In most 4-spd manuals, it is 4th gear. They had no overdrive. In every T56 and TR6060 (Viper Transmissions) it has always been 4th gear. I've not seen any transmissions use 3rd 1.00 except for the 3-speed TH350/TH400 GM automatics. In the GM 2-spd Powerglide, it is 2nd gear 1.00.
Anyways... back to physics (Mech Eng degree here, minor in Physics)
Your statement is correct, if we are discussing turning the driveline at a constant speed. But, we are accelerating the driveline, not simply turning it. The quicker the rate of acceleration, the more power it requires to turn the driveline. For a similar example, consider a vehicle travelling 200+ mph, and the wind resistance that it sees. In order to accelerate from 200-220 mph, a car with more power can do so in a quicker amount of time. You may compare two vehicles that both can reach 220 mph, but the more powerful one would achieve it sooner, and fight the wind resistance (drivetrain loss) better.
Anyways... back to physics (Mech Eng degree here, minor in Physics)
Your statement is correct, if we are discussing turning the driveline at a constant speed. But, we are accelerating the driveline, not simply turning it. The quicker the rate of acceleration, the more power it requires to turn the driveline. For a similar example, consider a vehicle travelling 200+ mph, and the wind resistance that it sees. In order to accelerate from 200-220 mph, a car with more power can do so in a quicker amount of time. You may compare two vehicles that both can reach 220 mph, but the more powerful one would achieve it sooner, and fight the wind resistance (drivetrain loss) better.
Peer Block:
Maybe this will help
1. All manual transmissions have a direct drive and it is not dependent on gears.
2. That direct drive has nothing to do with gears, I feel like I have to be redundant.
3. When you are in direct drive the input and output shaft are COUPLED together. The only other gear that is rotating is the cluster gear, therefore, losses are at a minimum.
4. Virtually all manual transmissions have 4th gear as direct drive. If you disagree, name me three (4/5/6 speeds) that are not. BTW -what started this thread tangent was your claim that all dyno pulls are in 3rd gear.
5. I have seen uninformed dyno operators use third gear - they just did not know better, therefore, their offspring think 3rd gear is the correct gear.
6. I do not know if this was mentioned, but, the dynojet dyno does not directly measure HP, they measure torque, we then calculate the HP - I believe that is an accurate statement, if not, let me know..
Sorry about the tongue and cheek, but, you are are hard person to get to admit he was wrong. As far as my background, two engineering degrees, I have participated in well over 100 dyno pulls and I have a T56 torn apart right now and most important, I use the viper for its god given purpose - to race.
Maybe this will help
1. All manual transmissions have a direct drive and it is not dependent on gears.
2. That direct drive has nothing to do with gears, I feel like I have to be redundant.
3. When you are in direct drive the input and output shaft are COUPLED together. The only other gear that is rotating is the cluster gear, therefore, losses are at a minimum.
4. Virtually all manual transmissions have 4th gear as direct drive. If you disagree, name me three (4/5/6 speeds) that are not. BTW -what started this thread tangent was your claim that all dyno pulls are in 3rd gear.
5. I have seen uninformed dyno operators use third gear - they just did not know better, therefore, their offspring think 3rd gear is the correct gear.
6. I do not know if this was mentioned, but, the dynojet dyno does not directly measure HP, they measure torque, we then calculate the HP - I believe that is an accurate statement, if not, let me know..
Sorry about the tongue and cheek, but, you are are hard person to get to admit he was wrong. As far as my background, two engineering degrees, I have participated in well over 100 dyno pulls and I have a T56 torn apart right now and most important, I use the viper for its god given purpose - to race.
No, we're talking about dyno numbers and how they pertain to the viper, as well as other vehicles...but feel free to try to keep telling everyone what they are talking about since you know better.
Just watch it when your S2000 hits VTEC because it gets a bit squirrely with all those powers its producing.
Not all transmissions have a 1:1 exact match gear. Not sure how to state that any more plainly. You could say that "many" transmissions have a 1:1 gear, but you are wrong to say that all do. The hang up on gear ratio is ignoring the point of the post - that dyno numbers are not a very good way to compare vehicle performance among various generations of a particular car or cars in general.
Yeah, it is pretty mean for a honda.
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My post was not in relation to your prior comments. It was more or less calling out PeerBlocks ridiculous and uneducated S2000 rant, which happened to be mixed in with his other long winded nonsense.
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Nine Ball
Enthusiast
Jack's statements are correct. Dynojet inertial dynojet measure torque and monitor RPM, and use that to calculate horsepower. It is a simple mathematical formula.
HP = Torque x RPM ÷ 5252
Further proof to that, whenever you use a Dynojet and the RPM sensing lead doesn't work properly - you simply end up with a torque graph. Also, when you cannot get an RPM sensing lead on a diesel truck, you only end up with a torque graph.
HP = Torque x RPM ÷ 5252
Further proof to that, whenever you use a Dynojet and the RPM sensing lead doesn't work properly - you simply end up with a torque graph. Also, when you cannot get an RPM sensing lead on a diesel truck, you only end up with a torque graph.
ViperGeorge
Enthusiast
Agreed. Question is why do people believe that the amount of power loss to the drive train is proportional to the amount of power (or torque if you prefer) generated by the engine?
klamathpro
Viper Owner
I have personally Dyno'd at that exact Livernois location on that exact Dyno. I've had nothing but bad experiences at that place, but besides that, I have a Nitrous setup on my 94' and I could not get that Dyno to show any more than an 81HP increase. I have a ROE B&B Catback and smooth tubes and went from 375RWHP to 405RWHP. But when tuning my Nitrous I tried every possible jet combination and even changed the foggers and went there on two separate occasions and could not get that Dyno to show any better than 486RWHP. They even convinced me to buy a new bottle, which it turned out I didn't need. The torque was correct and showed 589 but the HP numbers never seemed right. It didn't matter whether I setup for 100 shot or 150 shot, it was like the SAE corrected numbers hit a wall. I wouldn't trust that Dyno for any reliable numbers.
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